There are many types of data communication networks, such as local and wide area networks (LANs and WANs), which connect together a multiplicity of computers. LANs connect computers which are close together and WANs connect computers which are far apart, respectively. LANs are implemented in a number of protocols, such as ETHERNET, Token Ring and Fiber Distributed Data Interface (FDDI). A more recent type of network protocol is the asynchronous transfer mode (ATM) protocol which is useful for both LANs and WANs. ATM networks, which are networks based on the ATM protocol, are connection-oriented in a manner similar to the telephone system.
Unfortunately, the various networks are incompatible with each other and therefore, if a user wants to take advantage of the qualities of the ATM networks, he must remove his old network and install a new ATM one.
Furthermore, most networks are not easily reconfigured. Typically, the workstation at which one person works is fixed in his room and is part of only one group of computers. For example, the groups might be the accounting and the engineering departments. If the user moves to a different room, the network has to be reconfigured, typically through bridges and routers, in order to access his new location. Similarly, if he changes groups but stays in the same room, the network has to be reconfigured. Any change typically also requires extensive management involvement.